AL-Ni-RARE EARTH ELEMENT ALLOY SPUTTERING TARGET

ABSTRACT

An Al-base alloy sputtering target consisting Ni and one or more rare earth elements, wherein there are 5.0×10 4 /mm 2  or more compounds whose aspect ratio is 2.5 or higher and whose equivalent diameter is 0.2 μm or larger, when a cross sectional surface perpendicular to the plane of the target is observed at a magnification of 2000 or higher.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. Ser. No. 11/341,531(now U.S. Pat. No. 7,803,238), filed Jan. 30, 2006, which claimspriority to JP 2005-037937, filed Feb. 15, 2005.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an Al—Ni-rare earth element alloysputtering target, and more particularly, to such an Al—Ni-rare earthelement alloy sputtering target which can be produced favorably evenwhen the target is to be made large and with which it is possible torealize stable sputtering which does not accompany major warp of thetarget.

While the sputtering target according to the present invention isapplicable to an interconnection film which forms a liquid crystalpanel, an organic EL panel or the like for use in a television set, alaptop computer, a monitor or other display, a reflection film, arecording film and the like for use in the field of optical recording,an interconnection film and the like in the field of semiconductordevices, use of the sputtering target according to the present inventionfor a liquid crystal panel will be described below as a typicalapplication.

2. Description of the Related Art

A liquid crystal panel of the active matrix type includes a TFT arraysubstrate which uses thin film transistors (TFTs) as switching elementsand includes pixel electrodes (transparent conductive film) andinterconnection portions which may be scanning lines, signal lines andthe like, an opposed substrate which includes a common electrode and isdisposed over a predetermined distance facing the TFT array substrate,and a liquid crystal layer which is injected between the TFT arraysubstrate and the opposed substrate.

The signal lines in the liquid crystal panel are sections which areelectrically connected with the pixel electrodes, and are generally madeof aluminum alloy. However, direct contact of the aluminum alloy (film)and the pixel electrodes produces aluminum oxide or the like, which isan insulation material, at the interface between the two and increasesthe electrical resistance there, a conventional solution to which isgenerally interposition of a film of refractory metal, such as Mo, Cr,Ti and W, as barrier metal between the aluminum alloy and the pixelelectrodes. In the meantime, the recent years have seen an attempt for asimplified producing process by means of omission of such a film ofhigh-melting-point metal and direct connection of the signal lines(aluminum alloy) and the pixel electrodes (transparent conductive film),and use of Al—Ni alloy for example as the aluminum alloy has beenproposed for reduction of the insulation material such as aluminum oxideand hence reduction of the electrical resistance (Patent Document 1; JP,2004-214606, A). Patent Document 1 also describes addition of Nd, Y, Feor the like as the third element makes it possible to enhance the heatresisting property of the interconnection film and improve theelectrical characteristics owing to smaller crystal grains and smallerintermetallic compounds in the structure.

Sputtering is generally used to form a thin film such as theinterconnection film above. Sputtering is a method according to whichplasma discharge is developed between a substrate and a target materialwhich serves as a film material, gas ionized by the plasma dischargecollides with the target material, the atoms of the target material areejected and accumulated as a thin film on the substrate and isadvantageous in that it achieves production of a thin film of the samecomposition as that of the target material unlike where a vacuumdeposition or AIP method is used.

Targets for production of the aluminum alloy film which have been so farproposed include the aluminum alloy having substantially reduced crystalgrain diameters according to Patent Document 2 (JP, 11-106905, A), veryfine compounds as those described in Patent Document 3 (JP, 2001-214261,A), Patent Document 4 (JP, 10-199830, A), etc. It is shown thatremarkably fine and small crystal grains or compounds reduce splashingduring film deposition and secure the uniform composition and filmthickness of the thin resultant film.

By the way, while the larger size of a liquid crystal display panel orthe like urgently demands increase of the size of a target forfabrication of the liquid crystal display panel, manufacturing of alarge-size target still needs reduced splashing, better characteristicsof a thin film to produce, and additionally, suppressed warp of thetarget attributable to heating during producing or use.

Warp of the target which occurs during producing may be warp of a plateat the stage of mechanical processing due to the residual stress whichremains after rolling or straightening, thermal deformation duringbonding to a cooling plate, etc., and if such deformation is excessive,not only the accuracy of the product but the productivity as welldeteriorate. Meanwhile, thermal deformation which occurs during useincludes deformation caused by repeated heating and cooling during filmdeposition, and such excessive deformation during use causes a problemthat a solder material which bonds the target with the cooling platecracks, the target locally fails to get cooled and the solder materialmelts and gets peeled off from the cooling plate.

The present invention has been made in light of the problems above, andaccordingly, aims at providing an Al—Ni-rare earth element alloysputtering target which does not accompany major deformation (warp)during producing and use, and can be produced precisely and efficientlyeven when the target is to be made large, and with which it is possibleto realize stable film deposition.

SUMMARY OF THE INVENTION

The target according to the present invention is an Al-base alloysputtering target containing Ni and one or more rare earth elements,wherein there are 5.0×10⁴/mm² or more compounds whose aspect ratio is2.5 or higher and whose equivalent diameter is 0.2 μm or larger, when across sectional surface perpendicular to the plane of the target isobserved at a magnification of 2000 or higher.

It is preferable that when the cross sectional surface perpendicular tothe plane of the target is observed at a magnification of 2000 orhigher, (a) the major axis direction of 80% or more of the compounds arewithin the range of ±30 degrees with respect to the direction which isparallel to the plane of the target, and (b) the number of bulkycompounds whose equivalent diameter exceeds 5 μm is 500/mm² or fewer.

For improvement of the heat resisting property, the rare earth elementis one or more elements selected from the group consisting of Nd, Y andDy. The aspect ratio in this context is (the maximum length)/(the lengthalong the direction orthogonal to the maximum length) of each compound.

According to the target of the present invention, even when used as alarge-size sputtering target, the target does not get deformed (warp)greatly even during rolling, bonding to a cooling plate and repeated usefor film deposition.

This makes it possible to precisely produce a target of a specified sizein an easy manner. This also attains easy bonding to a cooling plate andallows omission of straightening. Further, this suppresses cracking of asolder material between a target material and a cooling plate due torepeated heating and cooling during use and prevents separation of thesputtering target from the cooling plate, which in turn securesefficient and excellent deposition of an Al alloy interconnection andelectrode films or the like for a long time during steps of producing aliquid crystal display for instance.

While aiming at solving the problems associated with a large-size,target which warps particularly greatly, the present invention isapplicable of course also to a medium or small target which does notwarp as much as a large target does.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an SEM photograph (taken at a magnification of 2000) of across sectional surface of a conventional sputtering target; and

FIG. 2 is an SEM photograph (taken at a magnification of 2000) of across sectional surface of the sputtering target according to thepresent invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The inventors of the present invention devoted themselves to developmentof an Al—Ni-rare earth element alloy sputtering target which is used fordeposition of a useful an Al—Ni-rare earth element alloy thin film,which does not accompany major deformation (warp) during producing anduse, and can be produced precisely and efficiently even when the targetis to be made large, and with which it is possible to realize excellentsputtering. As a result, the inventors made the present invention basedon the findings that the existence of compounds herein defined within atarget would serve the purpose.

Describing more specifically, the inventors found that the existence ofcompounds whose aspect ratio was 2.5 or higher and whose equivalentdiameter was 0.2 μm or larger which were observed in a cross sectionalsurface perpendicular to the plane of a target would sufficientlysuppress deformation of the target.

The aspect ratio is set to 2.5 or higher as the compounds above arestronger than that of an Al matrix and are believed to contribute toimprovement of the strength of the target, and also because it has beenconfirmed that the existence of such compounds which appear rod-shapedin a cross sectional surface of the target in particular effectivelyincreases the strength than the existence of circular (sphere-like)compounds does. FIG. 1 shows, as a comparison, an SEM photograph (shotat three freely chosen locations where the thickness is from (¼)tthrough (¾)t of the thickness t of the target) of a cross sectionalstructure of an Al-0.6 at % Nd alloy target. When compounds observed ina cross sectional surface of the target are shaped like circles as shownin FIG. 1, it is difficult to sufficiently prevent deformation.

Even when the aspect ratio of the compounds is 2.5 or higher, if thecompounds are not large enough to a certain extent or larger, thecompounds will not sufficiently contribute to improvement of thestrength of the target and will not satisfactorily exhibit thedeformation preventive effect. Noting this, the present inventionrequires the existence of such compounds whose aspect ratio is 2.5 orhigher and whose equivalent diameter is 0.2 μm or larger (hereinafterreferred to as the “specified compounds”).

A requirement in accordance with the present invention is that a crosssectional surface perpendicular to the plane of a target observed at amagnification rate of 2000× at least or higher shows 5.0×10⁴/mm² or morespecified compounds. This is because if the number of the specifiedcompounds is less than this, it is not possible to sufficiently enhancethe strength of the target and securely suppress deformation. Thespecified compounds preferably exist in the amount of 6.0×10⁴/mm² ormore, and more preferably, 8.0×10⁴/mm² or more.

The number of the specified compounds may be found by observing andshooting the cross sectional surface perpendicular to the plane of thetarget at a magnification of 2000 at least as described above using SEMequipment and by analyzing the image of thus obtained SEM photographs.Sections to observe should not include a surface layer portion of thecross section, and observation of those sections where the thickness isfrom (¼)t through (¾)t of the thickness t of the target is recommended.During observation, the target should be observed at a few places(preferably at three or more locations) and an average value should beused.

FIG. 2 shows for reference an SEM photograph (shot at three freelychosen locations where the thickness is from (¼)t through (¾)t of thethickness t of the target) of the cross section of an Al-2 at % Ni-0.6at % Nd alloy target which satisfies the requirements above. Accordingto FIG. 2, it is seen that there are numerous rod-shaped compoundsunlike in FIG. 1. The gray compounds shaped like circular plates in FIG.2 do not satisfy the requirements above and are believed to be hardlyinfluential over improvement of the strength of the target. Thosecompounds shaped like circular plates should nevertheless be reduced innumber down to a recommendable level, as such compounds when bulky couldadversely affect film deposition as described later.

It is preferable that the major axis direction of the specifiedcompounds mentioned above is oriented along the rolling direction(namely, the direction of the plane of the target) when observed withinthe cross sectional surface perpendicular to the plane of the target ata magnification of 2000 or higher. When the specified compounds arefound to align along the parallel direction to the plane of the targetwhen observed within the cross sectional surface perpendicular to theplane of the target, defects attributable to pushing during mechanicalprocessing are shallow. This also suppresses abnormal discharge duringinitial use of the target, and prevents a deteriorated yield of FPDs(flat panel displays), unsatisfactory operation capabilities and thelike caused by defects in the thin film.

More specifically, it is desirable that the major axis direction of 80%or more of the specified compounds (which are compounds whose aspectratio is 2.5 or higher and whose equivalent diameter is 0.2 μm orlarger) are within the range of ±=30 degrees with respect to thedirection which is parallel to the plane of the target. Preferably, 85%or more of the specified compounds described above satisfy therequirement, and more preferably, the major axis direction of 90% ormore of the specified compounds are within the range of ±30 degrees withrespect to the direction which is parallel to the plane of the target.

For suppression of initial abnormal discharge during film deposition, itis recommended not to allow the existence of bulky compounds. While thepresent invention is characterized in permitting the existence of thespecified compounds which are large enough to a certain extent orlarger, the excessively large size of the specified compounds developabnormal discharge at the stage of sputtering during initial use of thetarget. Further, since the specified compounds above are hard, when thespecified compounds are pushed in during machine work, defects could beproduced. In addition, not only the specified compounds described abovebut bulky compounds shaped like circular plates as those shown in FIG. 2could also result in inconvenience during film deposition. Hence, it isrecommendable to suppress the number of bulky compounds whose equivalentdiameter exceeds 5 μm down to 500/mm² or less, irrespective of theshapes of the compounds (aspect ratios). The number of such bulkycompounds should be preferably reduced down to 300/mm² or less.

The orientation of the compounds above, the number of the bulkycompounds above and the like may be identified by observing and shootingthe cross sectional surface perpendicular to the plane of the target, atan increased magnification of 2000 at least as described above using theSEM equipment above and by analyzing the image of thus obtained SEMphotographs. In this instance as well, it is recommended to observe andshoot at plural locations where the thickness is from (¼)t through (¾)tof the thickness t of the target.

Although the present invention does not specify a method of producingthe sputtering target described above, a producing method which utilizesspray forming is recommended among the conventionally performed methods.This is because producing in accordance with this method easily producesa sputtering target containing the compounds specified in the presentinvention and thus produced target is of a uniform material in which analloy element is dissolved or dispersed evenly in Al which is the matrixphase.

A producing method which utilizes spray forming may be the followingprocess. That is, a melting material is dropped down from a nozzle, N₂gas for example is sprayed against the droplets, thereby pulverizing thematerial, and an intermediate material (whose concentration isapproximately from 50 to 60%) which is called a pre-form is made whilethe powdery material is yet to completely coagulate. This intermediatematerial is then encapsulated, degassed, pressed using an HIP (HotIsostatic Pressing) machine, forged into a plate-shaped material, rolledso that the plate thickness is approximately the same as that of thetarget, annealed and then mechanically processed.

To obtain the specified compounds above, it is recommendable to controlthe diameter of the nozzle and the spray gas pressure (hereinafterreferred to as the “gas pressure”) particularly at the spray formingstep for adjustment of the cooling speed. This is because the compoundsspecified in the present invention are not obtained by rolling whichwill be described later and because it has been experimentally verifiedthat the shapes and the sizes of these compounds are determined by aspray forming condition.

As for the nozzle diameter and the gas pressure, generally speaking, thenozzle diameter (φ) is from 2.5 to 10 mm and the gas pressure is from0.3 to 1.5 MPa to obtain an Al alloy material by spray forming. However,it is important in the present invention to strictly control the nozzlediameter (φ) to 3.0 through 5.5 mm (preferably the diameter (φ) is from3.3 through 4.5 mm) and strictly control the gas pressure in the rangefrom 0.6 through 0.9 MPa (or preferably from 0.65 through 0.85 MPa).

When the nozzle diameter is smaller than 3 mm, the flow rate of themolten Al alloy slows down and the cooling speed increases relative tothe flow rate, and therefore, compounds will not grow almost at all inone direction but rather stay round and compact, which means it will bedifficult to obtain the specified compounds. On the contrary, when thenozzle diameter is beyond 5.5 mm, the flow rate of the molten Al alloybecomes faster and the cooling speed slows down relative to the flowrate, and therefore, compounds will become bulky. Since this will reducethe number of the compounds, it will be impossible to secure the enoughnumber of the specified compounds.

Meanwhile, when the gas pressure is lower than 0.6 MPa, the coolingspeed slows down, which is not desirable as compounds will become bulkyand the number of the compounds will decrease as in the case of theexcessively large nozzle diameter described above. When the gas pressureexceeds 0.9 MPa, the cooling speed increases, compounds will remainshaped like spheres and it will be impossible to obtain compounds havinglarge aspect ratios as in the case of the excessively small nozzlediameter described above.

The present invention recommends controlling the shapes and the sizes ofthe compounds depending upon a spray forming condition and thereaftercontrolling the orientation of the compounds during subsequent rollingas described above. Control of the processing rate in particular amongrolling conditions is desirable as it makes it possible to arrange themajor axis direction of the specified compounds along the directionwhich is parallel to the plane of the target.

As for producing of an Al alloy target by rolling, generally adoptedconditions are the total working ratio of 45 to 85% and the processingrate per pass of 3 to 10%. However, for enhancement of the orientationof the compounds, it is desirable to increase the total processing rateand the processing rate per pass during rolling. Describing in specificdetails, the total processing rate of 60% or higher and the processingrate per pass of 5% or higher are recommended.

In the event that the total processing rate is lower than 60%, theorientation of the compounds does not sufficiently improve, which is notpreferable. The total processing rate is more preferably 70% or higher.From a standpoint of less burden upon equipment and prevention of alower productivity, the total processing rate of maximum 85% inaccordance with the generally required condition above.

Meanwhile, the processing rate per pass is preferably 5% or higher inthe present invention. If the processing rate per pass is lower thanthis, an area around the surface layer portion alone gets deformed butan area near the center of the plate thickness is rarely deformed, whichmakes it impossible to sufficiently enhance the orientation of thespecified compounds. The processing rate per pass is more preferably 7%or higher.

In the case of an Al alloy material to obtained by the material by sprayforming method described above, while it is possible to produce eitherby cold rolling or by hot rolling since the structure will not easilychange during these processing, for a higher processing rate per pass,processing in temperature range of low flow stress after heating the Alalloy material is effective, and therefore, hot rolling is preferable.The recommended heating temperature is from 350 through 450 degreesCelsius.

The other conditions such as those for spray forming, HIP, forging,rolling and the like may be generally accepted conditions (which aredescribed in JP, 9-248665, A for instance).

While the present invention is applicable to an Al-base alloy targetcontaining Ni and one or more rare earth elements and none of the amountof Ni and the type and the amount of the rare earth element isparticularly limited, where one plans to use the target according to thepresent invention for deposition of an electrode film of a displaydevice as that described earlier, 1 through 5 at % of Ni in anAl—Ni-rare earth element alloy target is recommended for reduction of aninsulation material which is produced at the interface between thusdeposited electrode film (aluminum alloy film) and pixel electrodes. Thetarget to which one or more types selected from the group consisting ofNd, Y and Dy has been added as rare earth elements enhances the heatresisting property of a deposited thin film without fail, which ispreferable. For this effect to be felt, it is recommended that theamount of the rare earth elements accounts for 0.1 through 3 at in theAl—Ni-rare earth element alloy target.

The present invention does not limit the shape or the size of the targetbut is rather applicable to targets having various shapes such as arectangular shape and a disk-like shape, noting the fact thatdeformation such as warp which occurs during producing or use of thetarget becomes more remarkable as the size of the target is larger, thepresent invention may be preferably applied to a large-size target whichmeasures 600 mm or longer along one side, which in turn willdramatically suppress such deformation and magnify the effect of thepresent invention.

The present invention will now be described more specifically inrelation to examples. The present invention however is not limited tothe examples below but may be implemented after appropriately modifiedto the extent meeting the intentions mentioned earlier and describedbelow. Those modifications all fall within the technical scope of theinvention.

Example 1

N₂ gas was blown against the Al alloy materials No. 1 through No. 10 andNo. 14 through No. 16 having the compositions shown in Table 1 duringspray forming under the conditions provided in Table 1, intermediatematerials (whose densities were approximately from 50 to 60%) wereconsequently obtained and then encapsulated and degassed, and thereafterpressed using an HIP machine. These were forged into plate-shapedmaterials, rolled (at the total processing rate of 80%, the processingrate per pass of 6 through 10% and the finish rolling temperature of 400degrees Celsius) so that the plate thickness would be approximately thesame as that of the final products (targets), annealed (400 degreesCelsius) and then mechanically processed, thereby obtaining Al alloyplates of 8 mm t×600 mm×800 mm. Other conditions for spray forming thanthose appearing in Table 1 are as follows:

-   -   Superheat: 200 degrees Celsius    -   Over pressure: initial . . . 0.003 MPa        -   end . . . 0.01 MPa

For comparison, the Al alloy materials No. 11 and No. 12 having thecompositions shown in Table 1 were dissolved within a vacuum inductionmelt furnace (i.e., inside a crucible of alumina filled with Ar gasunder 100 Torr) at 750 degrees Celsius (superheat), poured into(cylindrical) mold of graphite, and casted. This was followed byforging, rolling, annealing and mechanical processing as in the case ofproducing by the spray forming method described above, thereby obtainingAl alloy plates of the above size. As for No. 13 in Table 1, after Alpower, Al—Nd powder and Ni powder were mixed, the mixture wasHIP-processed and pressed, and thereafter forged, rolled, annealed andmechanically processed, thereby obtaining an Al alloy plate of the abovesize.

A cross sectional surface of each Al alloy plate thus obtained wasobserved with a microscope and the number of specified compounds wascounted. More specifically, using FE-SEM (Quanta 200 FEG, a fieldemission type scanning electron microscope manufactured by Phillips),under the conditions of the magnification of 2000 and the acceleratingvoltage of 5 kV, freely chosen three locations where the thickness wasfrom (¼)t through (¾)t within a cross sectional surface perpendicular tothe plane of each Al alloy plate were observed (each in the visual fieldof about 50 μm×about 60 μm), thus taking reflected electronic images.Using the WinROOF image analysis software (manufactured by MITANICORPORATION), image analysis of the digitized SEM photographs wasperformed, the number of compounds whose aspect ratio was 2.5 or higherand whose equivalent diameter was 0.2 μm or larger was counted, and anaverage value of the three visual fields in total was calculated andconverted into a count per 1 mm².

In addition, after holding each Al alloy plate on a hot plate heated to250 degrees Celsius for one hour, the maximum warp was measured. Thiswas followed by evaluation according to which the amount of warp of 2 mmor less meant suppressed deformation (◯), whereas the amount of warpover 2 mm meant significant warp (X). The Table 1 shows the results.

TABLE 1 Spray Forming Condition Nozzle Gas Amount of Diameter PressureCompound* No. Composition Process Method (mm) (MPa) (number/mm²) Warp 1Al—2at % Spray 3.5 0.8 110000 ∘ Ni—1at % Nd Forming 2 Al—2at % Spray 3.50.8 108000 ∘ Ni—1at % Y Forming 3 Al—2at % Spray 3.5 0.8 107000 ∘ Ni—1at% Dy Forming 4 Al—2at % Spray 3.5 0.8 61000 ∘ Ni—0.4at % Nd Forming 5Al—3at % Spray 3.5 0.8 58000 ∘ Ni—0.5at % Nd Forming 6 Al—3at % Spray3.5 0.8 70000 ∘ Ni—0.6at % Nd Forming 7 Al—4at % Spray 3.5 0.8 73000 ∘Ni—0.6at % Nd Forming 8 Al—2at % Spray 3.5 0.8 125000 ∘ Ni—2at % NdForming 9 Al—2at % Spray 3.5 0.8 63000 ∘ Ni—0.5at % Y Forming 10 Al—3at% Spray 3.5 0.8 81000 ∘ Ni—0.5at % Y Forming 11 Al—2at % Dissolution — —10000 x Ni—1at % Nd 12 Al—3at % Dissolution — — 5000 x Ni—0.6at % Nd 13Al—2at % Powder — — 1500 x Ni—1at % Nd 14 Al—3at % Spray 2.2  0.95 40000x Ni—0.6at % Nd Forming 15 Al—3at % Spray 6   0.5 27000 x Ni—0.6at % NdForming 16 Al—3at % Spray 6.5 0.8 25000 x Ni—0.6at % Nd Forming*Compounds whose aspect ratio was 2.5 or higher and whose equivalentdiameter was 0.2 μm or larger

Table 1 indicates the following. With respect to No. 1 through No. 10 inTable 1, since the compounds having the size specified in the presentinvention are present in the specified amounts, warp of the Al alloyplates would be minor even after heating, and therefore, when these areused as large-size sputtering targets, it would be possible to suppressthermal deformation during producing and use of the targets. On thecontrary, as for No. 11 through No. 17 in Table 1, since there are onlyan insufficient number of compounds having the size specified in thepresent invention, warp after heating will be significant, which willdecrease the productivity of producing the targets and lead toinconvenience during use.

Example 2

Al alloy materials obtained by spray forming under the recommendedconditions were rolled under various conditions, and the structures ofAl alloy plates and the influence over film deposition were examined.More specifically, after obtaining intermediate materials by sprayforming under similar conditions to those used for No. 1 through No. 10described in Example 1, the intermediate materials were encapsulated anddegassed, and thereafter pressed using an HIP machine. These were forgedinto plate-shaped materials, rolled under the conditions shown in Table2, annealed (400 degrees Celsius) and then mechanically processed,thereby obtaining Al alloy plates of 8 mm t×600 mm×800 mm.

As in Example 1, a cross sectional surface of each Al alloy plate thusobtained perpendicular to the plane of each Al alloy plate was observedwith a microscope, and the number of compounds whose aspect ratio was2.5 or higher and whose equivalent diameter was 0.2 μm or larger wascounted. As a result, it was confirmed that there were enough specifiedcompounds for each in this Example.

The orientation of the specified compounds was then identified from SEMphotographs. Describing in more details, the number of the specifiedcompounds whose major axis direction was beyond ±30 degrees with respectto the direction which was parallel to the plane of the target wassubtracted from the total number of the specified compounds and theresult was divided by the total number of the specified compounds, andthen the proportion (%) of the specified compounds whose major axisdirection was within the range of ±30 degrees with respect to thedirection which was parallel to the plane of the target was calculated.An average value of the three visual fields in total was thencalculated.

As for the number of bulky compounds, the compounds whose equivalentdiameter exceeded 5 μm were measured in the SEM photographs, an averagevalue of the three visual fields in total was calculated and convertedinto a count per 1 mm².

Next, targets of 5 mm t×φ101.6 mm were cut out from the Al alloy platesand subjected to a sputtering test under the conditions below. Througharc monitoring, the number of arcs during the first ten minutes ofsputtering was counted. Table 2 shows the results.

-   -   Ultimate vacuum: 4.0×10⁻⁴ Pa or less    -   Ar gas pressure: 0.3 Pa    -   Ar gas flow rate: 30 sccm (5×10⁻⁷ m³/s)    -   Sputter power: 500 W    -   Anode-cathode distance: 51.6 mm    -   Substrate temperature: room temperature

TABLE 2 Rolling Conditions Amount of Total Processing Ratio of BulkyProcessing Rate Aligned Compounds Number Rate Per Pass Temp Components(number/ of No. Composition (%) (%) (° C.) (%) *1 mm²) *2 Arcs 1 Al—2at% 80 6-10 400 86 3.2 30 Ni—1at % Nd 2 Al—2at % 80 6-10 400 90 3 29Ni—1at % Y 3 Al—2at % 80 6-10 400 93 2.6 23 Ni—1at % Dy 4 Al—2at % 806-10 400 91 2.7 25 Ni—0.4at % Nd 5 Al—3at % 80 6-10 400 82 4.1 35Ni—0.5at % Nd 6 Al—3at % 80 6-10 400 94 2.5 19 Ni—0.6at % Nd 7 Al—2at %55 3-5  400 75 3 58 Ni—1at % Nd 8 Al—2at % 55 3-5  400 70 3.1 62 Ni—1at% Y 9 Al—3at % 55 3-5  400 69 4 69 Ni—0.6at % Nd *1 Of compounds whoseaspect ratio was 2.5 or higher and whose equivalent diameter was 0.2 μmor larger, those whose major axis direction was within the range of ±30degrees with respect to the direction which was parallel to the plane ofthe target *2 Bulky compounds whose equivalent diameter was over 5 μm

Table 2 indicates the following. When there are the specified amount ofcompounds specified in the present invention, the major axis directionof the specified compounds is aligned with the direction which isapproximately parallel to the plane of a target as in the case of No. 1through No. 6 in Table 2 and production of bulky compounds issuppressed, it is possible to secure the mechanical strength,sufficiently suppress development of arcs during the initial stage ofsputtering and achieve more stable sputtering.

1. An Al-base alloy sputtering target comprising Ni and one or more rare earth elements, wherein there are 5.0×10⁴/mm² or more compounds at least containing Ni or rare earth elements whose aspect ratio is 2.5 or higher and whose equivalent diameter is 0.2 μm or larger, when a cross sectional surface perpendicular to the plane of the target is observed at a magnification of 2000 or higher.
 2. An Al-base alloy sputtering target according to claim 1, wherein (a) 80% or more of the compounds have the major axis direction on the plane vertical to the plane of the target and are within the range of ±30 degrees with respect to the direction which is parallel to the plane of the target, and (b) the number of bulky compounds whose equivalent diameter exceeds 5 μm is 500/mm² or fewer.
 3. An Al-base alloy sputtering target according to claim 1, wherein the rare earth element is one or more elements selected from the group consisting of Nd, Y and Dy.
 4. An Al-base alloy sputtering target according to claim 2, wherein the rare earth element is one or more elements selected from the group consisting of Nd, Y and Dy. 